The present invention relates to a wire harness manufacturing apparatus for and method of automatically manufacturing a wire harness to be installed in an automotive vehicle, especially, sub-wire harnesses as constituents of the wire harness and a method of controlling a period of xe2x80x9ctact timexe2x80x9d in the wire harness manufacturing apparatus, too.
In Japanese Unexamined Patent Publication (kokai) No. 6-5132, there is disclosed an earlier art wire harness manufacturing apparatus where a wiring plate is transferred from one device as a module to the other device in order, while a wire harness is continuously assembled on the moving wiring plate.
Then, each modular device is constituted by a base, a processing mechanism mounted on the base and a transporting unit attached to the base.
Note, in the adjoining modular devices, the base of one modular device is adapted so as to be connectable with the base of the adjoining modular device.
Further, the transporting unit is provided with a portion for transporting the wiring plate in the base and a projecting portion. When it is required to connect the base of one modular device with the base of the adjoining modular, the projecting portion of the transporting unit is inserted into the base of the other device
In this way, as the conventional wire harness manufacturing apparatus has the plural modular devices provided for processes respectively and connected with each other, it is possible to increase or decrease the number of modular devices, corresponding to the constitution of the wire harness to be manufactured. Further, by arranging the modular devices of designated number in order, it is also possible to adjust the production capability in an optional process so as to cope with the wire harness being manufactured, thereby also corresponding to the change of design of the wire harness.
In the conventional wire harness manufacturing apparatus, however, since the plural devices as modules for processes are controlled independently of each other, it is difficult to balance the manufacturing loads among the constituent devices appropriately and therefore, there is a problem of occurrence of intermediate stocks among the processes.
Additionally, if the wire harness is subjected to the change of design or manufactured by another manufacturing line, it is necessary to not only alter the control data every devices but rearrange the constituent devices of the manufacturing line with an operator""s burden. In conclusion, the conventional wire harness manufacturing apparatus has a problem of wasting time in order to establish a new manufacturing line.
Under such a circumstance, it is therefore an object of the present invention to provide a wire harness manufacturing apparatus and a tact time controlling method thereof, both of which are capable of reducing the occurrence of intermediate stocks to the utmost and also facilitating a measure against the change of design of the wire harness or the change in manufacturing line itself, whereby it is possible to establish the manufacturing line in a remarkable short time if such a change is raised.
The object of the present invention described above can be accomplished by a wire harness manufacturing apparatus comprising:
plural manufacturing lines for respectively manufacturing plural sub-wire harnesses as constituents of a wire harness to be produced, each of the manufacturing lines consisting of plural constituent devices arranged in manufacturing order of each sub-wire harness;
plural line control devices provided for controlling operational processes of the manufacturing lines respectively, each of the line control devices being connected with the constituent devices of each of the manufacturing lines through a signal transmitting circuit; and
at least one system control device adapted so as to construct a signal transmitting network together with the line control devices, for controlling manufacturing loads among the plural manufacturing lines.
With the above-mentioned constitution, the wire harness is manufactured by plural manufacturing lines manufacturing sub-wire harnesses as the constituents of wire harness.
In operation, the plural manufacturing lines are controlled by the corresponding line control devices, while manufacturing loads among the manufacturing lines are balanced by the single system control device. Consequently, it is possible to operate the plural manufacturing lines while reducing so-called xe2x80x9cintermediatexe2x80x9d stocks existing among the respective manufacturing lines to the utmost.
While, manufacturing loads among the constituent devices in each manufacturing line are balanced by the line control device, whereby it is possible to operate the devices while reducing the intermediate stocks existing among the respective devices to the utmost.
In the present invention, preferably, each of the line control devices comprises:
a variable data recording unit for recording variable data in the constituent devices and the variable data altered later;
a line central processing unit for judging whether constitution of the constituent devices in the manufacturing line is appropriate by comparing production reserving data inputted from the system control device with the variable data, the line central processing unit further judging whether the manufacturing line modified on the basis of the former judgment is appropriate or not;
a line display unit for displaying both variable data recorded on the variable data recording unit and result of judgment obtained by the line central processing unit;
a line input unit for inputting an operation starting signal and the altered variable data obtained by modifying the manufacturing line in accordance with a result of judgment by the line central processing unit; and
a production command unit for inputting the production reservation data generated from the line central processing unit as a result of the line input unit""s inputting the operation start signal, the production command unit sequentially outputting the production command signal based on the production reservation data to each of the constituent devices; and
wherein the system control device comprises:
a data base for the wire harness to be produced;
a common data recording unit for recording common data in common with the plural manufacturing lines and the sequent common data added later;
a system input unit for inputting product data of the wire harness and the added common data;
a system central processing unit for
making out an article numbers"" list of the sub-harnesses constituting the wire harness by comparing the product data with the data recorded in the data base;
comparing the data of the sub-wire harnesses of respective article numbers with the above common data and the variable data in the respective data recording units in the line control devices in order to determine the manufacturing line in charge of each sub-wire harness with the article number; and
making out the production reservation data for each manufacturing line determined, on the basis of the product data;
a system display unit for displaying the product data, the common data, the variable data, the article numbers"" list, the determined manufacturing lines in charge and the production reservation data; and
a reservation data transmitting unit for transmitting the production reservation data to the line central processing unit of the line control device of the manufacturing line being determined.
In the above-mentioned apparatus, when inputting the product data of the wire harness being produced through the system input unit, then the article numbers"" list of the sub-wire harnesses constituting the wire harness is formed by the system control device. Additionally, by the system control device, the manufacturing line in charge of the sub-wire harness of each article number is determined and the production reservation data is formed for every manufacturing line. Since the production reservation data is being formed while balancing the manufacturing loads among the manufacturing likes, it is possible to reduce the intermediate stocks existing among the respective manufacturing lines to the utmost. The production reservation data is outputted from the system control device and inputted to the line control device of each manufacturing line.
Further, when the rearrangement of the constitution is executed, the variable data due to the rearrangement is inputted into the line input unit and registered in the variable data recording unit.
In each of the manufacturing lines, preferably, the line control device includes a tact time recording unit for recording tact time of the corresponding manufacturing line being inputted by the line input unit; the line central processing unit is constituted with one function to calculate waiting time being inputted through the system control device and the tact time thereby to determine cycle time of the corresponding manufacturing line and another function to transmit the cycle time to the production command unit upon inputting an operation starting signal; and the production command unit is constituted with a function to output signals so that the corresponding manufacturing line works in accordance with the cycle time; and preferably, the system central processing unit is constituted with one function to comparatively calculate respective tact time registered in the tact time recording units of the plural line control devices thereby to determine respective waiting time of the plural manufacturing lines and another function to transmit the respective waiting time to the reservation data transmitting unit; and the reservation data transmitting unit is constituted with a function to transmit each waiting time to the line central processing unit of the corresponding line control device.
In the above-mentioned arrangement, since the respective manufacturing lines are adapted so as to operate in accordance with the cycle time calculated by the waiting time and the tact time, it is possible to reduce the intermediate stocks existing among the respective manufacturing lines to the utmost.
According to the invention, there is also provided a method of controlling tact time of the wire harness manufacturing apparatus mentioned above, the method comprising the steps of:
measuring the tact time for each of the manufacturing lines by preliminarily operating the manufacturing line in advance of its practical operation;
allowing the line control device of the manufacturing line to input the tact time for registration;
calculating the waiting time for the manufacturing line by the system control device, on the basis of the tact time recorded in the line control device;
transmitting the calculated waiting time to the line control device of the manufacturing line; and
both calculating the cycle time of the manufacturing line in charge and controlling the operation of the manufacturing line in accordance with the calculated cycle time, by the line control device.
According to the method, since the tact time is measured by operating the manufacturing line actually and thereafter, the waiting time and the cycle time are obtained on the basis of the tact time, it is possible to obtain the cycle time with high accuracy. Therefore, the manufacturing lines are controlled so as to reduce the intermediate stocks among the manufacturing lines due to the manufacturing loads to the utmost, by the respective cycle time with high accuracy.
In the above-mentioned method, it is more preferable that the line control device automatically measures the tact time of the practical operation after finishing the operation of the corresponding manufacturing line at constant cycles and replaces the registered tact time with the tact time of the practical operation for registration; the system control device calculates new waiting time for each of the manufacturing lines on the basis of the tact time of the practical operation registered in the line control device and transmit the new waiting time to the line control device of the manufacturing line; and that the line control device calculates new cycle time of the manufacturing line and controls the operation of the manufacturing line in accordance with the new cycle time.
In this case, since the tact time, the waiting time and the cycle time are reviewed for corrections after the actual operation of the constant number of cycles, it is possible to manage the respective cycle time of the manufacturing lines with high accuracy.
According to the invention, there is also provided a wire harness manufacturing method, comprising the steps of:
inputting product data of the wire harness to be manufactured with a system input unit;
reading out record data from a data base to a system central processing unit when inputting the product data, and making an article number""s list of sub-wire harnesses constituting the wire harness to be manufactured by comparing the record data with the product data;
reading out common data from a common data recording unit to the system central processing unit and variable data from variable data recording units of line control devices, and determining at the system central processing unit which of the manufacturing lines takes charge of manufacturing the sub-wire harness of each article number by comparing both the common data and variable data with the data of the sub-wire harness of each article number in the article number""s list;
making at the system central processing unit, production reservation data for each manufacturing line determined in the above way, on the basis of the product data;
transmitting the production reservation data for each of the manufacturing lines from the system central processing unit through a reservation data transmitting unit to a line central processing unit of a corresponding line control device;
reading out variable data from the variable data recording unit to the line central processing unit, comparing the variable data with the production reservation data at the line central processing unit to judge whether or not a constitution of constituent devices in an existing manufacturing line is appropriate, and changing the constitution of devices of the present manufacturing line on the basis of a result of a judgment of the line central processing unit;
transmitting the production reservation data from the line central processing unit to a production command unit on receipt of the operation starting signal from a line input unit, and transmitting a production command signal based on the production reservation data from the production command unit to each of the constituent devices; and
activating the respective constituent devices in the manufacturing line to manufacturing a corresponding sub-wire harnesses in accordance with the production reservation data.
In the above-mentioned method, since the production reservation data is being formed while balancing the manufacturing loads among the manufacturing lines, it is possible to reduce the intermediate stocks existing among the respective manufacturing lines to the utmost.